Our New 2013 Jaguar XF SC V6
#21
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The other difference in the V6 SC is the flat torque curve. NA engines have torque curves that droop as rpm increases.
The V6 not only feels quicker than the 4.2 V8, it is quicker. Also, once the V6 gets off the line it is very quick, that 8 spd keeps the engine in that flat torque curve and the car just sprints.
I'd be very interested to compare the new V6 with the NA 5.0 V8 over say 40 mph to 70 mph, in full automatic mode, and see if the V6 is quicker. I think it would be.
#22
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The other difference in the V6 SC is the flat torque curve. NA engines have torque curves that droop as rpm increases.
I'd be very interested to compare the new V6 with the NA 5.0 V8 over say 40 mph to 70 mph, in full automatic mode, and see if the V6 is quicker. I think it would be.
I'd be very interested to compare the new V6 with the NA 5.0 V8 over say 40 mph to 70 mph, in full automatic mode, and see if the V6 is quicker. I think it would be.
Torque is great at take off, once you get moving, hp is what you need.
The 5 liter engine has extra 40hp and 48lb-ft torque. That's a significant amount of power increase.
#23
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Though I think the 3.0 SC is a great engine, like Dan Quayle was told, "You're no Jack Kennedy" - and the "3.0 SC is no 5.0 V8". It will be behind, but not by much, any speed or quickness comparison with the NA 5.0. As far as a comparison of passing acceleration,
Car and Driver tested a 5.0 XF (2010) and a 2013 XJ 3.0 SC (rear wheel drive). Their curb weights were basically identical. The results (5.0/3.0): 30-50 mph - 2.6/3.2. 50-70 mph - 3.5/4.1. That's 23% quicker 30-50, and 17% quicker 50-70. The margin would be quite a bit wider with the 3.0 AWD version.
The fact that the 5.0 has 380lb-ft at 3500 RPM versus the 3.0 SC at 332 lb-ft between 3500-5000 means that there is an extremely wide band of RPMs where the 5.0 will have more torque, by a significant amount. The talk about the 3.0 being as quick or quicker than the 5.0 just isn't going to hold water. It's quick, but not that quick.
Car and Driver tested a 5.0 XF (2010) and a 2013 XJ 3.0 SC (rear wheel drive). Their curb weights were basically identical. The results (5.0/3.0): 30-50 mph - 2.6/3.2. 50-70 mph - 3.5/4.1. That's 23% quicker 30-50, and 17% quicker 50-70. The margin would be quite a bit wider with the 3.0 AWD version.
The fact that the 5.0 has 380lb-ft at 3500 RPM versus the 3.0 SC at 332 lb-ft between 3500-5000 means that there is an extremely wide band of RPMs where the 5.0 will have more torque, by a significant amount. The talk about the 3.0 being as quick or quicker than the 5.0 just isn't going to hold water. It's quick, but not that quick.
Last edited by rbobzilla; 07-03-2013 at 12:48 PM.
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jagular (07-03-2013)
#24
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On the contrary, once you get moving torque won't matter much.. It would be much easier for the car with more hp to outrun the one with less.
Torque is great at take off, once you get moving, hp is what you need.
The 5 liter engine has extra 40hp and 48lb-ft torque. That's a significant amount of power increase.
Torque is great at take off, once you get moving, hp is what you need.
The 5 liter engine has extra 40hp and 48lb-ft torque. That's a significant amount of power increase.
Torque is force which is why it has to be expressed as lb ft ( not ft lbs which is work, a different idea). Only force can accelerate. F= ma or a=F/m more usefully.
For acceleration the difference in torque developed by the engine as multiplied by the transmission yields the acceleration of a given mass. In the helpful post setting out the actual numbers achieved by Car and Driver the mass is considered to be identical (weight is proportional to mass by the acceleration of local gravity, denoted g in lateral accelerations for example, and may be used interchangeably at the same elevation and coordinates on the earth's surface) and given the 5.0 superior torque over the applicable rpm of the 6 spd compared to the torque of the V6 SC even with the 8 spd is sufficient to produce the superior roll on acceleration.
I'm a little surprised frankly, but numbers is numbers.
I cannot find those numbers, is there a link to the C&D article(s)?
Last edited by jagular; 07-03-2013 at 02:40 PM.
#25
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Not really, hp is just torque x 5250. In that sense torque is horsepower.
Torque is force which is why it has to be expressed as lb ft ( not ft lbs which is work, a different idea). Only force can accelerate. F= ma or a=F/m more usefully.
I'm a little surprised frankly, but numbers is numbers.
I cannot find those numbers, is there a link to the C&D article(s)?
Torque is force which is why it has to be expressed as lb ft ( not ft lbs which is work, a different idea). Only force can accelerate. F= ma or a=F/m more usefully.
I'm a little surprised frankly, but numbers is numbers.
I cannot find those numbers, is there a link to the C&D article(s)?
2010 Jaguar XF 5.0 Premium Road Test – Review – Car and Driver
Car and Driver test results for 2010 XF are as it follows:
C/D TEST RESULTS:
Zero to 60 mph: 5.1 sec
Zero to 100 mph: 12.0 sec
Zero to 120 mph: 17.6 sec
Street start, 5–60 mph: 5.3 sec
Standing ¼-mile: 13.6 sec @ 106 mph
I was actually being conservative with my numbers. 0-60 is 5.1 as tested.
Will look for a test with the new V6SC model.
Last edited by Executive; 07-03-2013 at 03:11 PM.
#26
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It's X5252 to be exact.
2010 Jaguar XF 5.0 Premium Road Test – Review – Car and Driver
Car and Driver test results for 2010 XF are as it follows:
C/D TEST RESULTS:
Zero to 60 mph: 5.1 sec
Zero to 100 mph: 12.0 sec
Zero to 120 mph: 17.6 sec
Street start, 5–60 mph: 5.3 sec
Standing ¼-mile: 13.6 sec @ 106 mph
I was actually being conservative with my numbers. 0-60 is 5.1 as tested.
Will look for a test with the new V6SC model.
2010 Jaguar XF 5.0 Premium Road Test – Review – Car and Driver
Car and Driver test results for 2010 XF are as it follows:
C/D TEST RESULTS:
Zero to 60 mph: 5.1 sec
Zero to 100 mph: 12.0 sec
Zero to 120 mph: 17.6 sec
Street start, 5–60 mph: 5.3 sec
Standing ¼-mile: 13.6 sec @ 106 mph
I was actually being conservative with my numbers. 0-60 is 5.1 as tested.
Will look for a test with the new V6SC model.
In any event, let's enjoy!
#28
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It seems Jaguar left the XF with a bit of a void now that the 5.0 non-SC is gone. In my opinion, the 5.0 non-SC gives you a lot of power, but not ridiculously so. Now, if you want a V8, you have to step up to the 5.0SC, which has way too much power for a sedan. If I were buying today, it would be a tough choice, especially considering the price difference between the V6 and V8 SC model ($53k vs. $68k). The 5.0 non-SC at around $60k, was right in between the two and hit the sweet spot in price and power.
#29
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Car and Driver uses very aggressive starts to get those numbers. They take the torque converter to stall speed and then launch. I think they even get a one foot rollout lopped off the number.
Jaguar's factory number is much more realistic.
Also, unless you are at sea level you'll not see those numbers on your stopwatch. The supercharged engine should get the same numbers at any elevation from sea level to at keast 10,000 ft. Which reminds me, I drive at 3,500 ft where I live so my V6 SC will accelerate much better than my 4.2, which is what I'm comparing it to, seat of the pants. I also have yet to floor it, 900 km to go before I do that. Air density at my house is only 90% of that at sea level. Drop 10% off those hp and torque numbers for the NA 5.0 and you'll see why my car feels quick when compared to the 5.0 driven at the same elevation.
Jaguar's factory number is much more realistic.
Also, unless you are at sea level you'll not see those numbers on your stopwatch. The supercharged engine should get the same numbers at any elevation from sea level to at keast 10,000 ft. Which reminds me, I drive at 3,500 ft where I live so my V6 SC will accelerate much better than my 4.2, which is what I'm comparing it to, seat of the pants. I also have yet to floor it, 900 km to go before I do that. Air density at my house is only 90% of that at sea level. Drop 10% off those hp and torque numbers for the NA 5.0 and you'll see why my car feels quick when compared to the 5.0 driven at the same elevation.
Last edited by jagular; 07-04-2013 at 09:15 AM.
#30
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Car and Driver uses very aggressive starts to get those numbers. They take the torque converter to stall speed and then launch. I think they even get a one foot rollout lopped off the number.
Jaguar's factory number is much more realistic.
Also, unless you are at sea level you'll not see those numbers on your stopwatch. The supercharged engine should get the same numbers at any elevation from sea level to at keast 10,000 ft. Which reminds me, I drive at 3,500 ft where I live so my V6 SC will accelerate much better than my 4.2, which is what I'm comparing it to, seat of the pants. I also have yet to floor it, 900 km to go before I do that. Air density at my house is only 90% of that at sea level. Drop 10% off those hp and torque numbers for the NA 5.0 and you'll see why my car feels quick when compared to the 5.0 driven at the same elevation.
Jaguar's factory number is much more realistic.
Also, unless you are at sea level you'll not see those numbers on your stopwatch. The supercharged engine should get the same numbers at any elevation from sea level to at keast 10,000 ft. Which reminds me, I drive at 3,500 ft where I live so my V6 SC will accelerate much better than my 4.2, which is what I'm comparing it to, seat of the pants. I also have yet to floor it, 900 km to go before I do that. Air density at my house is only 90% of that at sea level. Drop 10% off those hp and torque numbers for the NA 5.0 and you'll see why my car feels quick when compared to the 5.0 driven at the same elevation.
Anyway, it also shows that there is still loss at altitude for forced induction - just not as much. In the case of turbos, there is more lag as the density is lower and it take a little longer to get spooled up and have to turn at faster rpm to maintain the same boost. Superchargers don't suffer the lag issue, but since they rely directly on energy from the engine itself, the argument is that there is less energy from the engine, therefore less to turn the Roots blower... General rule of thumb is 3% loss of power per 1000 ft for non aspirated and half of that for forced induction. Maybe a little more than half for supercharged engines.
Last edited by rbobzilla; 07-04-2013 at 11:47 AM.
#31
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My SAAB Aero loses no power with elevation until you get over 10,000 ft. The reason is the type of boost pressure control. SAAB uses strictly detonation limited boost pressure curve profile. Only when the air gets too thin so as to be outside the optimal pressure capacity of the compressor does air pressure matter.
Lobe type superchargers are less efficient than centrifugal compressors but boost better at low "compressor" rpm. Centrifugal compressors tend to have fairly narrow efficiency ranges but as long as they remain within that efficiency band keep building boost as compressor rpm increases.
One big advantage to modern lobe superchargers is the ability to fit oversized "compressors" and modulate boost pressure by dump valving (bypass actually) using software and valving invented to control over boosting of turbos.
Lobe type superchargers aren't compressors, strictly speaking, but displacement type air pumps. The pressure rises in the intake pipe downstream of the supercharger, not in the supercharger itself. Turbos (and centrifugal superchargers like Vortex) actually compress the air inside the compressor snail. Mechanical lobe type superchargers cannot fully compensate for altitude or elevation effects as they just move air at the pressure it arrives at their intakes to the outlet of the supercharger, so less air to begin with means lower pressure built up at the output. Only by providing for, in effect, over boost can such superchargers adjust for elevation effects. The Jaguar V6 must have significant over boost capability to preserve power output with increasing elevation. That's certainly my impression.
Lobe type superchargers are less efficient than centrifugal compressors but boost better at low "compressor" rpm. Centrifugal compressors tend to have fairly narrow efficiency ranges but as long as they remain within that efficiency band keep building boost as compressor rpm increases.
One big advantage to modern lobe superchargers is the ability to fit oversized "compressors" and modulate boost pressure by dump valving (bypass actually) using software and valving invented to control over boosting of turbos.
Lobe type superchargers aren't compressors, strictly speaking, but displacement type air pumps. The pressure rises in the intake pipe downstream of the supercharger, not in the supercharger itself. Turbos (and centrifugal superchargers like Vortex) actually compress the air inside the compressor snail. Mechanical lobe type superchargers cannot fully compensate for altitude or elevation effects as they just move air at the pressure it arrives at their intakes to the outlet of the supercharger, so less air to begin with means lower pressure built up at the output. Only by providing for, in effect, over boost can such superchargers adjust for elevation effects. The Jaguar V6 must have significant over boost capability to preserve power output with increasing elevation. That's certainly my impression.
Last edited by jagular; 07-04-2013 at 05:23 PM.
#32
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It's X5252 to be exact.
2010 Jaguar XF 5.0 Premium Road Test – Review – Car and Driver
Car and Driver test results for 2010 XF are as it follows:
C/D TEST RESULTS:
Zero to 60 mph: 5.1 sec
Zero to 100 mph: 12.0 sec
Zero to 120 mph: 17.6 sec
Street start, 5–60 mph: 5.3 sec
Standing ¼-mile: 13.6 sec @ 106 mph
I was actually being conservative with my numbers. 0-60 is 5.1 as tested.
Will look for a test with the new V6SC model.
2010 Jaguar XF 5.0 Premium Road Test – Review – Car and Driver
Car and Driver test results for 2010 XF are as it follows:
C/D TEST RESULTS:
Zero to 60 mph: 5.1 sec
Zero to 100 mph: 12.0 sec
Zero to 120 mph: 17.6 sec
Street start, 5–60 mph: 5.3 sec
Standing ¼-mile: 13.6 sec @ 106 mph
I was actually being conservative with my numbers. 0-60 is 5.1 as tested.
Will look for a test with the new V6SC model.
Not really, hp is just torque x 5250. In that sense torque is horsepower.
Torque is force which is why it has to be expressed as lb ft ( not ft lbs which is work, a different idea). Only force can accelerate. F= ma or a=F/m more usefully.
For acceleration the difference in torque developed by the engine as multiplied by the transmission yields the acceleration of a given mass. In the helpful post setting out the actual numbers achieved by Car and Driver the mass is considered to be identical (weight is proportional to mass by the acceleration of local gravity, denoted g in lateral accelerations for example, and may be used interchangeably at the same elevation and coordinates on the earth's surface) and given the 5.0 superior torque over the applicable rpm of the 6 spd compared to the torque of the V6 SC even with the 8 spd is sufficient to produce the superior roll on acceleration.
I'm a little surprised frankly, but numbers is numbers.
I cannot find those numbers, is there a link to the C&D article(s)?
Torque is force which is why it has to be expressed as lb ft ( not ft lbs which is work, a different idea). Only force can accelerate. F= ma or a=F/m more usefully.
For acceleration the difference in torque developed by the engine as multiplied by the transmission yields the acceleration of a given mass. In the helpful post setting out the actual numbers achieved by Car and Driver the mass is considered to be identical (weight is proportional to mass by the acceleration of local gravity, denoted g in lateral accelerations for example, and may be used interchangeably at the same elevation and coordinates on the earth's surface) and given the 5.0 superior torque over the applicable rpm of the 6 spd compared to the torque of the V6 SC even with the 8 spd is sufficient to produce the superior roll on acceleration.
I'm a little surprised frankly, but numbers is numbers.
I cannot find those numbers, is there a link to the C&D article(s)?
Horsepower = (Torque x RPM)/ 5252
One could say that Horsepower is a by product of torque and rpm as it literally is.
And what "Jagular" was getting at, in reference to the flat torque curve for the forced induction motor, is if you hold your torque for longer into the rpm band, will translate into more horsepower. This is what is commonly referred to as area under the curve, where instead of referencing peak values only, you reference total usable power.
0-60 are great indicators of a car's performance, a quarter mile test gives you that much more (not just the time, but the trap speed), and finally your 50 - 70, which some care reviews will provide, give you a definitive feel of passing/ overtaking power...
At the end of it all, chances are the older 5.0 n/a V8 was overall faster than the SC V6, but that's not saying the V6 is a slouch. and the V6 boasts much better fuel economy ratings...
#33
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Simply put: torque produces acceleration while horsepower produces speed.
Power states the capacity of the engine to perform work over time. Exert the torque for a specified period of time and the power number will indicate the ability of that engine to produce and maintain higher and higher speeds.
This is why high torque engines are valued in North America where high speeds are just not permitted in practice. In Europe high speeds may not be permitted legally but enforcement practices mean they are permitted in reality. Not so in North America where driving at European speeds will soon have you walking.
Power states the capacity of the engine to perform work over time. Exert the torque for a specified period of time and the power number will indicate the ability of that engine to produce and maintain higher and higher speeds.
This is why high torque engines are valued in North America where high speeds are just not permitted in practice. In Europe high speeds may not be permitted legally but enforcement practices mean they are permitted in reality. Not so in North America where driving at European speeds will soon have you walking.
#34
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